JPH0636740A - Ion implanter - Google Patents

Abstract

PURPOSE:To monitor the purity measurement of an ion beam reaching a wafer in an ion implanter on the in-line basis at the production site. CONSTITUTION:A disk 11 is provided with two kinds of targets coupled with it. The target (A) 12a is mounted with a wafer 13, and it is used for normal ion implantation. The target (B) 12b is provided with a slit 16 partitioning an ion beam 15 into the preset quantity and size, a fine target 17 radiated with the ion beam 15, a cooler 18 cooling the fine target 17, and a mass spectrometer 19. The target (B) 12b is used for measuring the ion beam purity, the ions generated when the ion beam 15a passing through the slit 16 ionizes the fine target 17 are analyzed by the mass spectrometer 19, and the purity of the ion beam 15 is measured.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ion implanter. In recent years, in the VLSI manufacturing process, the ion implantation method has been widely used in the process of introducing impurities into a semiconductor substrate. Since the ion implantation method has high controllability and reproducibility with respect to the amount and depth of implantation of impurities, it is an effective means for reproducibly and precisely controlling the amount of impurities and the junction depth.

[0002]

2. Description of the Related Art FIG. 2 is a schematic view of an ion implantation apparatus. In the figure, 21 is an ion source, 22 is a mass analyzer, 23 is a mass separation slit, 24 is an accelerating tube, 25 is a Faraday cup, 26 is a disk, and 27 is a wafer.

The operation of the ion implanter shown in FIG. 2 will be described below. Since the ions extracted from the ion source 21 contain a large amount of impurity ions other than the desired ions, such as the components of the ion source gas, they are selected by the mass analyzer 22 to obtain an ion beam consisting of only the desired ions. .

The ions selected by the mass analyzer 22 pass through the mass separation slit 23, the acceleration tube 24, and the Faraday cup 25, reach the wafer 27 mounted on the scanning mechanism, and are injected into the wafer 27. To be done. Since a disk type is the most common mechanism for scanning a wafer, it will be referred to as a disk 26 hereinafter.

The disk 26 is rotating at a speed of about 1000 rpm, and the wafer 27 is attached to the disk 26 by the centrifugal force generated by the rotation of the disk 26. The ion beam selected by the mass spectrometer 22 theoretically consists of only one kind of pure ion. However, in reality, the material (mainly an aluminum alloy) forming the mass separation slit 23 and the acceleration tube 24 is sputtered by the ion beam, and the impurity ions generated by this sputtering phenomenon are generated by the mass analyzer 2.
It mixes in the ion beam selected by 2. Therefore, many impurity ions are mixed in the ion beam reaching the wafer 27.

With the high integration of semiconductor devices, it has been required to improve the purity of the ion beam reaching the wafer 27, and it has become necessary to reduce the number of impurity ions in the ion beam.

Conventionally, the purity of the ion beam reaching the wafer 27 is measured by implanting ions into a test wafer, removing the test wafer from the manufacturing line, and bringing it into another facility for atomic absorption analysis or 2 It was conducted by instrumental analysis such as secondary ion mass spectrometry.

[0008]

The conventional method for measuring the purity of an ion beam reaching a wafer has to take a test wafer from the production line and bring it to another facility, which is time-consuming. there were.

Further, since instrumental analysis such as atomic absorption analysis and secondary ion mass spectrometry is used, the cost is increased.
There was also a problem. SUMMARY OF THE INVENTION It is an object of the present invention to solve the above problems and provide an ion implanter capable of monitoring the purity of an ion beam reaching a wafer in-line at a manufacturing site.

[0010]

In order to achieve the above object, an ion implantation apparatus according to the present invention is provided with at least an ion source, a mass analyzer, an accelerating tube, and a mechanism for mounting a wafer. In the implantation apparatus, the mechanism for mounting the wafer includes two types of targets fitted to the first target, the first target on which the wafer is mounted, and the second target for mounting the wafer. A slit that divides the ion beam into a predetermined amount and size, a minute target irradiated with the ion beam, a cooler that cools the minute target, and a mass analyzer are provided, and the first target is used during normal ion implantation. Then, ion implantation is performed on the wafer placed on it, and when the ion beam purity is measured, the second target is used and the ions passing through the slit are used. Analyze ions over beam is generated when the ionizing small target by mass analyzer configured to measure the purity of the ion beam.

[0011]

In the ion implantation apparatus according to the present invention, the wafer mounting mechanism has two types of targets fitted therein. The first target is one on which a wafer is placed. The second target is provided with a slit that divides the ion beam into a predetermined amount and size, a minute target irradiated with the ion beam, a cooler for cooling the minute target, and a mass analyzer.

During normal ion implantation, the first
The target is mounted and the wafer placed on the target is ion-implanted. When measuring the ion beam purity, the first target is removed from the disk, the second target is fitted to the disk instead, and the ions generated when the ion beam passing through the slit ionizes the minute target are analyzed by a mass spectrometer. Then, the purity of the ion beam is measured.

Therefore, by using the silicon chip as the minute target, it is possible to analyze the purity of the ion beam that reaches the second target in the same state as when the silicon wafer is ion-implanted.

As a result, the ion beam purity analysis, which has been conventionally performed by expensive equipment analysis at other facilities, can be monitored in-line at the manufacturing site.

[0015]

FIG. 1 is a diagram showing the configuration of an embodiment of the present invention. The relationship between the disk and the target of the ion implantation apparatus according to the present invention is shown in a normal ion implantation state (FIG. 1A) and an ion implantation state. It is shown separately in the beam purity measurement state (FIG. (B)).

In the figure, 11 is a disk, 12 is a target, 13 is a wafer, 14 is a Faraday cup, 15 is an ion beam, 16 is a slit, 17 is a silicon chip, 18 is a cooler, and 19 is a mass spectrometer.

An embodiment of the present invention will be described below with reference to FIG. (1) Normal ion implantation state (see FIG. 1A) During normal ion implantation, the target (A) 12a on which the wafer 13 is placed is fitted on the disk 11 for use. At this time, the ion beam 15 passes through the Faraday cup 14 to reach the wafer 13, and ions are implanted into the wafer 13.

(2) Ion beam purity measurement state (see FIG. 1B) When measuring the purity of the ion beam 15, the target (A) 12a is removed from the disk 11 and the target (B) 12b is fitted instead. To do.

The purity of the ion beam 15 is measured as follows. The ion beam 15a of the ion beam 15 divided by the slit 16 provided in the target (B) 12b irradiates the silicon chip 17. At this time, the silicon chip 17 is sufficiently cooled by the cooler 18 and is not melted.

When the cooling function of the cooler 18 is stopped after the irradiation amount of the ion beam 15a to the silicon chip 17 becomes sufficient, the silicon chip 17 is melted by the energy of the ion beam 15a. Since it is in a vacuum, the silicon chip 17 into which the ions are injected by the ion beam 15a sublimes. At this time, a part to be ionized also occurs. The ionized substance is detected by the mass spectrometer 19 and the components thereof are measured to measure the purity of the ion beam 15a and thus the ion beam 15. As a mass spectrometer, the quadrupole mass spectrometer is compact and inexpensive, so it is easy to use.

As described above, in the present embodiment, since the silicon chip 17 is used as the minute target, the purity of the ion beam 15 can be analyzed in the same state as when the silicon wafer is ion-implanted.

Further, in order to measure the purity of the ion beam 15, only the target (A) 12a is removed from the disk 11 and the target (B) 12b is fitted in place of the target (A) 12a. The purity analysis of the ion beam 15 which has been performed by the analysis can be monitored in-line at the manufacturing site.

[0023]

According to the present invention, the ion implantation apparatus can monitor the purity of the ion beam reaching the wafer in-line at the manufacturing site. As a result, the ion implanter can be quickly maintained, so that the availability of the device can be improved and the manufacturing cost of the semiconductor device can be reduced.

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration of an embodiment of the present invention.

FIG. 2 is a schematic view of an ion implantation device.

[Explanation of symbols]

 11 Disk 12 Target 13 Wafer 14 Faraday Cup 15 Ion Beam 16 Slit 17 Silicon Chip 18 Cooler 19 Mass Spectrometer

Claims (1)

[Claims] 1. An ion implantation apparatus comprising at least an ion source, a mass spectrometer, an accelerating tube, and a wafer mounting mechanism, wherein the wafer mounting mechanism is of two types fitted to it. , A first target has a wafer placed thereon, and a second target has a slit that divides the ion beam into a predetermined amount and size, a minute target irradiated with the ion beam, A cooler for cooling the minute target and a mass analyzer are provided. At the time of normal ion implantation, the first target is used to perform ion implantation on a wafer placed on the first target, thereby ensuring ion beam purity. At the time of measurement, the second target is used, and the ions generated when the ion beam passing through the slit ionizes the minute target are separated by the mass spectrometer. An ion implanter characterized by analyzing and measuring the purity of the ion beam.